Programming system for machine tools or the like

ABSTRACT

A programming system for use in machine tools wherein a slide is reciprocable by a hydraulic motor which receives and discharges hydraulic fluid by way of a regulating valve on the slide. The valve has a spool which is reciprocable between two operative positions and a neutral position and has a radially extending follower which can be arrested by the projections of an indexible drum mounted adjacent to the path of the slide. The movements of the spool from its neutral position to a selected operative position (in which the motor receives fluid for moving the slide forwardly or rearwardly) are initiated by a control plunger secured to the follower and reciprocable in cylinder chambers of the housing in response to admission of pressurized control fluid by a four-way pilot valve. The follower moves against a first projection during forward movement of the slide to thereby return the spool from one operative position to neutral position, and against another projection during rearward movement of the slide to thereby return the spool from the other operative position to the neutral position. The nominal diameter of the plunger is a small fraction of the diameter of the spool.

United States Patent Bernd et a1.

July s, 1975 PROGRAMMING SYSTEM FOR MACHINE TOOLS OR THE LIKE [73] Assignee: G. L. Rexroth GrnbH, Lohr, Main,

Germany [22] Filed: July 26, 1973 [21] Appl. No.: 382,712

[30] Foreign Application Priority Data July 27, 1972 Germany 2236801 [52] U.S. Cl 91/35; 91/358 R; 91/374 [51] Int. Cl. F151) 21/02; F15b 13/16 [58] Field of Search 91/216 A, 358 R, 358 A, 91/374, 35

[56] References Cited UNITED STATES PATENTS 689,145 12/1901 Turner 91/358 R 1,179,822 4/1916 Gransden 91/358 R 1,912,184 6/1930 Ferris et al 91/358 R 2,216,973 10/1940 Harrington et al 91/358 R 2,358,361 9/1944 Svenson 91/35 FOREIGN PATENTS OR APPLICATIONS 1,150,452 4/1969 United Kingdom 91/358 R Primary Examiner-Paul E. Maslousky Attorney, Agent, or Firm-Michael S. Striker 5 7] ABSTRACT A programming system for use in machine tools wherein a slide is reciprocable by a hydraulic motor which receives and discharges hydraulic fluid by way of a regulating valve on the slide. The valve has a spool which is reciprocable between two operative positions and a neutral position and has a radially extending follower which can be arrested by the projections of an indexible drum mounted adjacent to the path of the slide. The movements of the spool from its neutral position to a selected operative position (in which the motor receives fluid for moving the slide forwardly or rearwardly) are initiated by a control plunger secured to the follower and reciprocable in cylinder chambers of the housing in response to admission of pressurized control fluid by a four-way pilot valve. The follower moves against a first projection during forward movement of the slide to thereby return the spool from one operative position to neutral position, and against another projection during rearward movement of the slide to thereby return the spool from the other operative position to the neutral position. The nominal diameter of the plunger is a small fraction of the diameter of the spool.

5 Claims, 2 Drawing Figures n La--- "Hard-.1". u. nn au-n...

PROGRAMMING SYSTEM FOR MACHINE TOOLS OR THE LIKE BACKGROUND OF THE INVENTION The present invention relates to programming systems in general, and more particularly to improvements in means for programming the operation of machine tools or the like, especially for programming the operation of machines wherein slides or analogous parts are movable in a predetermined sequence and through predetermined distances in accordance with a preselected schedule. Still more particularly, the invention relates to improvements in programming systems wherein one or more valves control the operation of one or more rotary or reciprocable hydraulic motors.

It is already known to provide in a programming system for machine tools or the like a regulating valve wherein a valve member (e.g., a spool) is movable between several positions and is permanently biased by a spring toward an operative position in which the valve member allows a hydraulic fluid to flow to and/or from a consumer, e.g., a double-acting hydraulic cylinder and piston unit or a rotary hydraulic motor. The valve member is rigid and coaxial with a follower which extends from the housing of the valve and can be arrested or displayed by the projections of an indexible programming drum or the like. Thus, and assuming that the valve is mounted on a slide or carriage whose movements are effected by a hydraulic motor receiving fluid by way of the valve, the follower can be arrested by a selected projection while the slide continues to move with the housing of the valve so that the housing moves relative to the valve member and the latter assumes another position, e.g., a neutral position in which the flow of fluid to and from the motor is interrupted so that the slide comes to a halt. The means for thereupon changing the position of the valve member relative to the housing so that the valve member can cause the motor to return the slide to a starting position includes a discrete pilot valve of identical nominal diameter which causes a control fluid to displace the valve member so that the latter assumes a different second operative position in which the motor for the slide is caused to return the slide to its starting position. Upon completion of such return movement of the slide, the valve member must be returned to its neutral position, normally by resorting to at least one additional valve member. The just described programming system is rather complex, bulky and expensive. Also, the projections of the indexible drum must displace the valve member against a very high resistance of pressurized control fluid act ing on the one or the other end face of the valve member.

SUMMARY OF THE INVENTION An object of the invention is to provide a novel and improved hydraulic flow regulating valve which can be used in programming systems for machine tools or the like as a less expensive and more reliable substitute for presently known regulating valves.

Another object of the invention is to provide novel and improved means for changing the position of the valve member in the improved regulating valve.

A further object of the invention is to provide a programming system which embodies the improved regulating valve and is capable of insuring that the valve regulates the flow of fluid to and/or from one or more consumers with a high degree of accuracy and reproducibility.

An additional object of the invention is to provide for the regulating valve a novel and improved control member (e.g., an indexible drum with one or more projections) which can insure that the valve member of the regulating valve returns to its neutral position from any one of several operative positions and which can be programmed to effect the movement of the valve member to its neutral position after the regulating valve covers a selected distance relative to the control member or vice versa.

Still another object of the invention is to provide novel and improved means for initiating the movements of the valve member of the regulating valve from neutral position to any of several operative positions independently of the control member.

A further object of the invention is to provide a novel and improved mounting for the follower of the valve member in a regulating valve of the above outlined character.

Another object of the invention is to provide a programming system for machine tools or the like which can be used to regulate the sequence, duration and extent of operations of one or more reciprocable or rotary hydraulic motors to thereby effect controlled movements of slides, carriages or the like.

The invention is embodied in a programming system for machine tools or the like, particularly for machine tools wherein one or more tool-supporting slides are movable relative to workpieces. The programming system comprises a control member (e.g., an indexible drum) having a plurality of projections movable to and from a predetermined position in response to actuation of the control member, and a hydraulic flow regulating valve including a housing, a valve member (e.g., a spool) which is reciprocable in the housing between a neutral position and two operative positions, a follower extending laterally from the housing and being rigid with the valve member, and a plunger which is secured to the follower and is movable in the housing by a pressurized control fluid to shift the valve member from the neutral position to a selected operative position. The housing is movable relative to the control member or vice versa, and the follower is in register with each projection which assumes the predetermined position to move the valve member from an operative position selected by the plunger back to the neutral position while the housing moves relative to the control member or vice versa after the follower has engaged a projection which assumes the predetermined position. The housing may be mounted on a slide which is movable by a double-acting hydraulic cylinder, and the valve member controls the flow of a pressurized working fluid to and from the double-acting cylinder, for example, in such a way that the cylinder moves the slide one direction in one operative position of the valve member and in the opposite direction in the other operative position of the valve member. To this end, the housing may be provided with a first opening which is connected to a source of pressurized working fluid, a second opening which is connected with a tank for such fluid, and two additional openings which are connected with the aforementioned double-acting cylinder or another suitable motor. The valve member seals the first and second openings from the additional openings when it assumes its neutral position.

The plunger is preferably reciprocable in parallelism with the valve member and its diameter is preferably a small fraction of the diameter of the valve member so that the control fluid which acts against the one or the other end of the plunger offers a relatively small resistance to movement of the valve member relative to the housing or vice versa while the follower engages a projection and the housing continues to move relative to the control member or the control member continues to move relative to the housing.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved programming system itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic elevational view of a programming system which embodies the invention, the regulating valve being shown in longitudinal section with the valve member in a neutral position; and

FIG. 2 is a plan view of the regulating valve as seen in the direction of arrow A shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, there is shown a programming system including a three-position fluid flow regulating valve having a housing I provided with a longitudinally extending bore 2 and having two end walls or covers 5, 6 which seal the respective ends of the bore 2. The latter receives a sleeve or shell 3 for a reciprocable valve member or spool 4 which is shown in a neutral position. The spool 4 has two cylindrical lands 4A and 4B which are respectively flanked by fluid flow regulating shoulders 4a, 4b and 4c, 4d. The land 4A between the shoulders 4a, 4b seals the inner ends of radial ports 3a and the land 48 between the shoulders 40, 4d seals the inner ends of radial ports 3b in the sleeve 3. The outer ends of the ports 30 communicate with an annular channel 7 which is machined into the periphery of the sleeve 3 and communicates with a first opening A which is connected with one chamber of the motor 90.

The outer ends of the ports 3b communicate with a second annular channel 8 which is also machined into the periphery of the sleeve 3 and communicates with a second opening B which is connected with the other chamber of the motor 90.

The sleeve 3 is further provided with diametrically extending bores 3c, 3d and 3e. The bores 3c communicate with an annular channel 9 and the bores 32 communicate with an annular channel 11. The channels 9 and 11 are machined into the periphery of the sleeve 3 and communicate with each other as well as with a low-pressure outlet T which is connected to a tank or reservoir, not shown. The bore 3d communicates with an annular channel 10 which is machined into the periphery of the sleeve 3 between the channels 7 and 8 and which is connected with a pump P or another source. The channels 9 and 11 are outwardly adjacent to the channels 7, 8, respectively and connected with the tank T or another reservoir.

The spool 4 has an extension 4e which includes a smaller-diameter median portion 4f having a diametrically extending conical bore 43 for the conical inner end portion 510 of a follower 51. That part of the conical portion 51a which extends from the portion 4g is externally threaded and meshes with a nut 12 so that the follower 51 is rigidly secured to the spool 4. The follower 51 has a diametrically extending bore 13 for a shifting plunger 14. The latter is surrounded by washers l5 and carries pins 16 which prevent the washers 15 from moving away from each other. The washers 15 are immediately adjacent to the respective ends of the bore 13 so that the follower 51 is coupled to and shares without play all movements of the shifting plunger 14 or vice versa.

The end portions of the plunger 14 are reciprocable in chambers or bores 17, 18 provided therefor in the housing 1 and extending in parallelism with the bore 2. It will be noted that the area of each end face of the plunger 14 is a very small fraction of the area of each end face 4ff of the spool 4. The end faces 140 are acted upon by a control fluid (e.g., oil) whose flow is regulated by a four-way control valve 70.

The chamber 17 communicates with a first conduit PS1 for control fluid by way of a first passage including bore 19 in the cover 5 and bores 20a, 20b in the main portion of the housing 1. The chamber 18 communicates with a second conduit PS2 for control fluid by way of a second passage including a bore 21 in the cover 6, a larger-diameter bore and bores 22a, 22b in the main portion of the housing 1. The median portion of the chamber 17 communicates with a bore 23 which, in turn, communicates with an outlet 25 for leak fluid by way of an annular channel 24 machined into the periphery of the sleeve 3. The median portion of the chamber 18 communicates with a bore 26 which, in turn, communicates with a second outlet 28 for leak fluid by way of a further annular channel 27 of the sleeve 3. The channel 27 further communicates with a channel 30 in the internal surface of the sleeve 3 by way of radial bores 29, and the channel 24 further communicates with a compartment 32 by way of radial bores 31 in the sleeve 3. The compartment 32 constitutes the left-hand end portion of the bore 2 adjacent to the cover 5 and communicates with a similar compartment 34 by way of an axial passage 33 in the spool 4. The compartment 34 constitutes the right-hand end of the bore 2 adjacent to the cover 6. It will be seen that the compartments 32 and 34 are connected with the outlet 25 for leak fluid, i.e., that the fluid in these compartments is maintained at atmospheric pressure. Since the channel 30 is connected with the outlet 28 for leak fluid, any hydraulic jamming or tilting of the extension 4e in the sleeve 3 is impossible or highly unlikely. Moreover, the channel 30 cannot discharge pressurized fluid into a cavity 36 which is provided in the sleeve 3 and is open to the atmosphere. The cavity 36 sontains the threaded part of the conical portion 51a and the nut 12.

The outer portion 51b of the follower 51 is connected with a head 510 by means of a screw 37 or another suitable fastener. The head Slc has facets 51d shown in FIG. 2 which can be engaged by the displacing projections 40 of a rotary control member here shown as an indexible drum 41. The follower 51 is shifted axially of the sleeve 3 through a predetermined distance when a projection 40 is rotated so as to move in the direction of an arrow 45 (FIG. 2). The surface 400! of the projection 40 then engages one of the facets 51d and the inclination of such facet determines the extent to which the spool 4 is shifted lengthwise by the follower 51. This causes the spool to assume one of its two operative positions. The arrangement is preferably such that the openings A, B are connected with the source of pressurized fluid and tank (or vice versa) before the projection 40 moves beyond the head 51c. This insures a smooth start of an operation, e.g., the movement of a slide or carriage 80 in a machine tool or the like.

The opening A of the housing 1 is connected with one chamber of the motor 90 (which may be a doubleacting cylinder and piston unit) and with the channel 7 and the opening B is connected to the other chamber of the motor 90 and with the channel 8. The channel is connected to a pump P or another source of pressurized hydraulic fluid and the channels 9, 11 are connected to a reservoir or tank T.

The extension 4e has two cylindrical guide portions 40 and 4E which are slidable in the sleeve 3. The latter can be said to constitute a portion of the housing 1.

The operation:

In the illustrated neutral position of the spool 4, the lands 4A and 48 respectively seal the ports 3a and 3b of the sleeve 3. Since the channels 7 and 8 are sealed from the channels 9, l0 and 11, the motor 90 cannot receive pressurized fluid from the source of pressurized fluid and cannot discharge fluid to the tank.

If the valve 70 is thereupon actuated to connect the conduit PS2 with a source of control fluid and the conduit PS1 with a tank for control fluid, the control fluid flows from the conduit PS2 into the cylinder chamber 18 and acts against the respective end face 14a of the plunger 14 so that the latter moves the follower 51 in a direction toward the cover 5 whereby the spool 4 leaves the neutral position of FIG. 1 and assumes a first operative position in which the land 4A allows pressurized working fluid to flow from a source P and via the aforementioned channels 10, 7 and opening A to displace the piston in the motor 90. At the same time, the land 43 allows fluid to flow from the motor 90, via opening B channels 8 and 11 to the tank T. It is assumed that the carriage 80 for the regulating valve of FIG. 1 is the main slide of a machine tool and that the motor 90 serves to move the main slide 80 lengthwise. When the plunger 14 has caused the follower 51 to move the spool 4 to the aforementioned first operative position in which the conduit A admits pressurized fluid to one chamber of the motor 90 and the conduit B returns fluid from the other chamber of the motor 90 to the tank, the motor 90 moves the main slide 80 and the valve of FIG. 1 in a direction to the left so that the follower 51 moves toward a projection 40' of the indexible control drum 41. The drum 4] is adjacent to the path of movement of the main slide 80 and is indexible through predtermined angles and at predetermined intervals in accordance with a preselected program. when the surface Sle of the head 51c reaches the projection 40 and the main slide 80 continues to move in a direction to the left, the follower 51 is arrested and the housing 1 moves relative to the spool 4 so that the latter moves (relatively speaking) back toward the neutral position of FIG. 1. Thus, the connection between the channel 7 and the source P of pressurized fluid on the one hand, and the channel 8 and the tank T on the other hand is interrupted whereby the piston of the motor 90 is arrested and the main slide 80 (with the regulating valve of FIG. 1) comes to a halt. The force which is needed to return the spool 4 from the first operative position back to the neutral position is relatively small because such force is opposed only by the pressure of control fluid which acts against the relatively small righthand end face 14a of the plunger 14.

If the valve is thereupon actuated to connect the conduit PS1 with the source of pressurized control fluid and to simultaneously connect the conduit PS2 with the tank for control fluid, pressurized fluid flows from the conduit PS1 into the chamber 17 and causes the plunger 14 to move toward the cover 6. The follower 51 entrains the spool 4 so that the latter leaves its neutral position and moves toward a second operative position in which the channel 7 is connected with the tank T and the channel 8 is connected with the source P of pressurized working fluid.

Therefore, the motor 90 moves the main slide in the opposite direction so that the regulating valve of FIG. I advances toward the projection 40" of the drum 41. When the surface Sle' (see FIG. 2) of the head 51c reaches the projection 40", the follower 51 comes to a halt and thereby arrests the spool 4 while the housing 1 continues to move in a direction to the right, as viewed in FIG. 1. Therefore, the spool 4 reassumes its neutral position and seals the motor from the source of pressurized fluid as well as from the tank so that the main slide 80 comes to a halt.

If the nature of treatment of workpieces in the machine is controlled by the programming system including the drum 41 and the regulating valve of FIG. 1 is such that the main slide 80 must move beyond the position determined by the projection 40" of the drum 41, the drum 41 is indexed so that the projection 40" is moved out of the path of the follower 51 while the control fluid in the chamber 17 remains under pressure so that the follower 51 is moved by the plunger 14 in a direction to the right and the channel 8 is again connected with the source P of pressurized working fluid and the channel 7 with the tank T. This causes the motor 90 to move the main slide 80 and the regulating valve of FIG. 1 in a direction to the right. Abrupt movement of the main slide 80 from its momentary position is prevented by the facets 51d of the head 51c. Thus, the plunger 14 maintains the head 51c in engagement with the projection 40" while the latter moves about the axis of the drum 41 whereby the making of a full connection between the channel 8 and the source of pressurized working fluid is delayed to the extent which is a function of the inclination of facets 51d.

The means for indexing the drum 41 so as to move selected projections 40 to a predetermined angular positions in which such projections extend into the path of movement of the follower 51 is not shown in the drawing.

The valve 70 can be a simple and inexpensive valve because it regulates the flow of a control fluid at a low pressure. Since the end faces 14a of the plunger 14 are very small when compared with the end faces 4ff of the spool 4, the displacement of the spool 4 from its neutral position can be effected with the exertion of a very small force. This is of importance in programming systems for machine tools.

An advantage of such mounting of the plunger 14 that it extends in parallelism with the spool 4 is that the follower 51 is held against rotation.

Without further analysis, the forgoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In a programming system for machine tools or the like the combination of a control member having a plurality of projections each movable to and from a predetermined position in response to actuation of the control member; a hydraulic flow regulating valve including a housing, a valve member having an extension provided with two cylindrical guide portions slidable in said housing, said valve member being reciprocable in said housing between a neutral position and two operative positions, a follower extending laterally from said housing and being fixedly secured to said extension of said valve member between said guide portions thereof, and a plunger parallel to said valve member fixedly secured to said follower and movable in said housing by a pressurized control fluid to shift said valve member from said neutral to a selected operative position; and means for moving said housing and said control memher relative to each other, said follower being in register with each projection which assumes said predetermined position to move said valve member from an operative position selected by said plunger back to said neutral position while said housing and said control member move relative to each other after said follower engages one of said projections in said predetermined position.

2. The combination of claim 1, wherein the diameter of said plunger is a small fraction of the maximum diameter of said valve member.

3. The combination of claim 1, wherein said follower has at least one inclined facet along which one of said projections of said control member moves while leaving said predetermined position in response to actuation of said control member and while said plunger urges said follower against said last mentioned projection whereby said valve member leaves said neutral position at the rate determined by the inclination of said facet.

4. The combination of claim 3, wherein said facet is provided on a separable exposed portion of said follower.

S. The combination of claim 1, further comprising four way control valve means for regulating the flow of said control fluid. 

1. In a programming system for machine tools or the like the combination of a control member having a plurality of projections each movable to and from a predetermined position in response to actuation of the control member; a hydraulic flow regulating valve including a housing, a valve member having an extension provided with two cylindrical guide portions slidable in said housing, said valve member being reciprocable in said housing between a neutral position and two operative positions, a follower extending laterally from said housing and being fixedly secured to said extension of said valve member between said guide portions thereof, and a plunger Parallel to said valve member fixedly secured to said follower and movable in said housing by a pressurized control fluid to shift said valve member from said neutral to a selected operative position; and means for moving said housing and said control member relative to each other, said follower being in register with each projection which assumes said predetermined position to move said valve member from an operative position selected by said plunger back to said neutral position while said housing and said contral member move relative to each other after said follower engages one of said projections in said predetermined position.
 2. The combination of claim 1, wherein the diameter of said plunger is a small fraction of the maximum diameter of said valve member.
 3. The combination of claim 1, wherein said follower has at least one inclined facet along which one of said projections of said control member moves while leaving said predetermined position in response to actuation of said control member and while said plunger urges said follower against said last mentioned projection whereby said valve member leaves said neutral position at the rate determined by the inclination of said facet.
 4. The combination of claim 3, wherein said facet is provided on a separable exposed portion of said follower.
 5. The combination of claim 1, further comprising four way control valve means for regulating the flow of said control fluid. 